A281662 (Denominator of Bernoulli(2*n)) read mod n.

0, 0, 0, 2, 1, 0, 6, 6, 6, 0, 6, 6, 6, 2, 12, 14, 6, 12, 6, 10, 0, 8, 6, 18, 16, 4, 15, 2, 6, 0, 6, 30, 9, 30, 31, 30, 6, 30, 3, 10, 6, 0, 6, 30, 3, 30, 6, 42, 6, 30, 42, 30, 6, 30, 33, 6, 42, 30, 6, 30, 6, 30, 42, 62, 1, 24, 6, 30, 42, 50, 6, 6, 6, 30, 72, 30, 61

Offset

1,4

Comments

Odd terms at: 5, 27, 33, 35, 39, 45, 55, 65, 77, 81, 99, 105, 121, etc. - Robert G. Wilson v, Jan 26 2017

Links

Seiichi Manyama, Table of n, a(n) for n = 1..1000

Formula

a(n) = A002445(n) mod n.

Mathematica

f[n_] := Mod[Denominator[BernoulliB[2 n]], n]; Array[f, 77] (* Robert G. Wilson v, Jan 26 2017 *)

Prog

(Ruby)
def bernoulli(n)
  ary = []
  a = []
  (0..n).each{|i|
    a << 1r / (i + 1)
    i.downto(1){|j| a[j - 1] = j * (a[j - 1] - a[j])}
    ary << a[0]
  }
  ary
end
def A281662(n)
  a = bernoulli(2 * n)
  (1..n).map{|i| a[2 * i].denominator % i}
end
(PARI) a(n) = denominator(bernfrac(2*n)) % n; \\ Michel Marcus, Jan 29 2017

Crossrefs

Cf. A002445, A106741, A281648.

Sequence in context: A271703 A276922 A129062 * A163936 A288874 A356545

Adjacent sequences: A281659 A281660 A281661 * A281663 A281664 A281665

Keyword

nonn

Author

Seiichi Manyama, Jan 26 2017

Status

approved